Don't Die A Sudden Death: Long QT Syndrome & Acquired Long QTS

What Is Long QT Syndrome?

Long QT Syndrome is a rare genetic heart defect which was scarcely recognized until recently. LQTS is a hereditary inborn medical condition that several people may be inflicted with, without even being aware of the condition or it's dangers.

LQTS can potentially be fatal if unknown about and can often lead to heart palpitations, fainting and even sudden death. Several people are known to have died suddenly and unexpectedly as a result of being inflicted with Long QT Syndrome and not knowing about it, some of them just young children.

Although LQTS is a rare condition, according to the Quinn Driscoll Foundation, up to 7,000 young people under the age of 18 die from an undetected heart condition every year in the United States alone. In addition, some people have suddenly and unexpectedly experienced sudden death as a result of LQTS whilst in situations such as walking down the street in public.

A person inflicted with LQTS that remains undiagnosed (and therefore without the necessary medical assistance) can sometimes incur sudden death as a result of being made to 'jump' by sudden external stimuli like a dog unexpectedly barking or a car driver unexpectedly beeping their horn as they drive past (depending on subtype). For this reason certain subtypes of LQTS can be devastating if not diagnosed. Also for this reason, natural hypnic jerks may pose a threat - a hypnic jerk is a sudden twitch often experienced by people during hypnagogia, just as they are falling asleep.

How Does LQTS Affect The Heart?

LQTS results in delayed repolarization of the heart after a heartbeat which creates a potential risk of TDP episodes (a type of irregular heartbeat originating from the ventricles). It is this risk which can lead to palpitations, fainting and sometimes worse, often caused by various external stimuli.

ECG's (Electro-Cardia-Grams) show prolongation of the QT interval, a measure of the time between the start of the Q-wave and the end of the T-wave in the heart's electrical cycle. The QT interval represents depolarization and repolarization of the left and right ventricles. In total there are currently thirteen known subtypes of LQTS.

Although LQTS can be drug induced after a patient is administered drugs such as Sotalol, Amiodarone, Haloperidol and/or Ziprasidone it's a likely factor that mutation of one of several genes is to have caused the susceptibility to prolonged QT interval, although some of these drugs do have prolonged QT interval as a rare side effect (Haliperidol and Ziprasidone).

The first documented case of Long QT Syndrome was in 1856, as described in Leipzig by Meissner - a deaf girl died after her teacher had shouted at her. Upon finding out about her death, her parents revealed that her brother who was also deaf had also died after a terrible fright.

The first case of LQTS documented by ECG was in 1957 by Anton Jervell and Fred Lange-Nielson and was described as Jervell and Lange-Nielson Syndrome. In 1979 the International Long-QT Syndrome Registry was established and allowed the numerous subtypes of LQTS to be evaluated and identified in a comprehensive manner.

The most common causes of LQTS are mutations in the genes KCNQ1 (LQT1), KCNH2 (LQT2), and SCN5A (LQT3).

What Treatment Is Available For Long-QT Syndrome?

First and foremost patients are told to avoid any medication that prolong the QT interval or lower the threshold for TDP. Beta Blockers are currently the most commonly administered drug to treat LQTS, as they decrease the risk of stress-induced arrhythmias. However, different medications may be administered depending on subtype.

Arrhythmia Termination can also be used to stop a life-threatening arrhythmia once it has already occurred though this involves an implantable cardioverter defibrillator (ICD). This is often used in patients who have had a cardiac arrest.

It is hoped that with further study of the underlying genetic factors that cause LQTS that more precise treatments will become available in the future.

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Jack Hagan 2 years agofrom New York

This stuff is truly helpful. I think this is the only detailed article about the topic of LQTS which can provide guidance to the people about the treatment of this syndrome. Thank you for sharing your valuable information with us.